1. Field of the Invention
The present invention relates to a traveling vehicle system. In particular, the present invention relates to a system in which a large number of traveling vehicles are controlled by a system server through a wireless LAN.
2. Description of the Related Art
The applicant proposed a system in which a large number of traveling vehicles such as overhead traveling vehicles are controlled by a system server on the ground. See, for example, JP2008-150135A. In this system, the system server provides an instruction of a target position or the like for each traveling vehicle in each control cycle of, e.g., 0.1 s, for allowing the traveling vehicle to execute the instruction. A wireless LAN is used suitably for communication between the traveling vehicles and the system server. In this system, although the wireless LAN is used, it is important to ensure that the instructions from the system server to the traveling vehicles do not have any delay, and reports from the traveling vehicles to the system server do not have any delay. If the instructions or the reports are delayed, the system server cannot control the traveling vehicles in real time. Therefore, for example, the traveling vehicles need to travel at lower velocity.